The present invention relates generally to suspension for supporting MR head slider over recording media. In particular, the present invention is in connection with head suspension assembly with multi layers.
The well-known and wildly used suspension includes a load beam having a base plate on a proximal end, a flexture on a distal end, a relatively rigid region adjacent to the flexure and a spring region between the base plate and rigid region. An air-bearing slider including the magnetic head is mounted to the flexture. The magnetic head is carried in a carrier or slider which is pushed gently against the surface of the disk when the disk is not rotating by the suspension assembly. When the disk begins to rotate at high speed, the slider is aerodynamically shaped to fly slightly above or very slightly away from the surface of this rotating disk. When the slider flies slightly away from the rotating disk, the magnetic head contained in the slider is then moved back and forth from track to track by the action of the support assembly holding the slider.
As disk drives have become smaller and smaller in size with increased data storage capacity, data recording density of the disk has gone up dramatically and the data tracks have become smaller and closer from each other. The magnetic heads and sliders have also decreased in size and weight. In order for the heads and sliders to be accurately positioned with respect to a desired track on the magnetic disk, the suspension must be precisely controlled and windage problem must be decreased as low as possible.
Therefore the choice of the spring rate of the bending region plays an important role in the design of the suspension. If the bending region is at high spring rate it will gain slight bending unless it is under a relatively strong force which makes it difficult to control the suspension. On the other side when the spring rate of the bending region is low the suspension can bend deeply under a relatively small force which obviously makes the control of the suspension easier. From this point of view it is desirable for the spring rate of the bending region of the suspension to be certainly controlled on the lower side.
Meanwhile the resonance characteristics must also be taken into consideration in the design of the suspensions. An inherent property of moving mechanical systems, however is their tendency to bend and twist in a number of different modes when driven back and forth at certain rates known as resonant frequencies. Such modes resulting in lateral or transverse motion of the head slider are particularly detrimental since they will cause the head slider to move from the desired track on the disk toward an adjacent track. There three primary modes which produce such motion known as the sway, first torsion and second torsion modes. Since the head suspension assemblies must be driven at high rates of speed in high performance disk drives the windage problems of the suspension and the issues of disk motor vibration will be raised because of mechanical characteristics. Therefore it is desirable for the resonant frequencies of a suspension to be as high as possible. Additionally it is noted that the position, shape and size of the roll or bend in the spring region of the suspension can effect the resonance characteristics.
Technicians in the filed of suspension are seeking various solutions to meet with all the requirements mentioned above. Traditional half-etching method is one among them. During the manufacturing process of the half-etching type of suspensions parts of the stainless steel are etched away along the suspension. However, because of the limits of the chemical etching technique, this will cause large variations in the remaining parts of the stainless steel which will bring detrimental effects to the performance of the suspensions.
Another solution is the four pieces type suspension. This kind of suspension is made up of four pieces known as the base plate hinged in the spring region, the load beam as the rigid region and the flexure. The four separated pieces are combined together to form the complete suspension. In the producing process of this type of suspension two parts of stainless steel are made at different thickness to satisfy different requirements at first. At a latter stage the two parts are combined together by laser welding. Although this method proves to be a satisfying solution to the questions raised in the half-etching type suspension the challenge it met with lies in the alignment of the two parts of different thickness.
An object of the present invention is to provide the suspension at a size which fits with the Femto slider that has smaller and lighter weight comparing to the Connectp, to pico slider.
A further object of the present invention is to provide a suspension which can balance between the contradict requirements of the thickness of the suspension in different sections.
The present invention discloses a suspension assembly comprised of a rectangular base plate section, a load beam and a flexure, said load beam can be further divided into a bending section near the base and a rigid beam section contiguous to said bending area, characterized in that said suspension assembly is made up of three layers, wherein an adhesive layer is sandwiched between two stainless steel layers with parts of one of said stainless layers etched off.
According to another aspect of the present invention a method for fabricating a multi-layer suspension assembly comprising:
a) Sandwiching the polyimide sheet with both sides covered with chemical adhesive reaction between two stainless steel sheets by heating and pressing before the three layer raw material is formed;
b) Etching off parts of the stainless steel along the longitude direction;
c) Etching off parts of the polyimide sheet remained to form individual three layer structures;
d) Forming the 3-layer suspensions after de-tab.